Embedded Software for SoC - Grupo de Mecatrônica EESC/USP

44 Chapter 4
In summary‚ the rules are defined as follows:
For every test statement the test is repeated at the beginning of the target
basic block of both the true and false clause. If the two versions of the
test (the original and the newly introduced) produce different results‚ an
error is signaled;
A flag ctrl_branch is defined in the program;
An integer value kj is associated with any procedure j in the code;
At the beginning of every procedure‚ the value kj is assigned to ctrl_branch;
a test on the value of ctrl_branch is introduced before and after any call
to the procedure.
2.1.4. Transformation tool – C2C Translator
We built a prototype tool‚ called C2C Translator‚ able to automatically implement
the above described transformation rules. The main objective is to transform
a program into a functionally equivalent one‚ but including capabilities
to detect upsets arising in the architecture’s sensitive area (internal registers‚
internal or external memory area‚ cache memory . . .).
The C2C Translator accepts as an input a C code source producing as output
the C code corresponding to the hardened program according to a set of
options. In fact‚ these options correspond to each group of rules presented in
Section 2 and they can be applied separately or together. Figure 4-5 shows
the entire flow of C2C translator. From the resulting C code‚ the assembly
language code for a targeted processor can be obtained‚ using an ad-hoc
compiler.